This application is based on and incorporates herein by reference Japanese Patent Application No. 2001-217252 filed on Jul. 17, 2001.
The present invention relates to a vehicular generator control system and method that has capability of changing its characteristics based on external electrical signals.
In a generator control system (regulator) for a vehicular alternating current power generator, a receiver unit is installed to communicate with external devices provided apart from the receiver unit. In such a regulator, it is proposed to control the characteristics of the regulator by indicating the characteristics with voltage pulse signals. In U.S. Pat. No. 6,014,016 (JP-A-10-51976), a regulator is constructed to receive signals indicating the regulator characteristics from an external device. In U.S. Pat. No. 6,137,247 (JP-A-11-262299), a regulator is constructed to change its characteristics in a wide range based on voltage pulse signals from an external device.
A generator is installed in an engine compartment of a vehicle. In the engine compartment, a large amount of electrical and magnetic noises are generated. Signals indicating the regulator characteristics from an external device need to be properly read by a receiver unit installed in the regulator even in such environment. Therefore, the receiver unit needs to be highly resistant to noise.
The present invention therefore has an objective to provide a vehicular generator control system (regulator) and method that uses signals indicating the regulator characteristics from an external device without being disturbed by transient noise.
The regulator of the present invention has a voltage control circuit and a receiver circuit. The voltage control circuit controls a field current of the generator so that an output voltage of the generator is regulated to a predetermined level. The receiver circuit periodically reads voltage pulse signals from an external device applied via a signal line.
Only when a variation in the voltage pulse width is within a predetermined range, the regulator controls the field current based on the characteristic values indicated with the pulse signal. As a result, the regulator can perform stable voltage control based on the indicated characteristics without being affected by transitory instability of the pulse signals.